System of recording



March 31, 1936. D. L. HAY 2,035,475

SYSTEM OF RECORDING Filed Feb. 21, 1955 INVENTOR Donald L Haj A T TORNE Y Patented Mar. 31, 1936 UNITED STATES PATENT OFFICE (Granted under the act or March amended April 30, 1928; 370 0. G. 757) This invention relates to improvements in the method of and apparatus for electrostatic and electromagnetic recording and particularly to the method and apparatus whereby the record may be made in any desired color.

An object of this invention is to provide a simple, convenient color recording system suitable for use in any type of recording apparatus wherein a permanent record in one or more colors is desired.

Another object of this invention is to provide a method and apparatus for color recording in which electrostatic and electromagnetic means are used to transfer the marking material directly on to a record sheet without the necessity of any intervening steps or apparatus.

With the above and other objects in view, the invention consists in the construction, combination and arrangement of parts as will be described more fully hereinafter.

Referring now to the drawing forming part of this specification: I

Fig. 1 is a schematic showing of an electrostatic recorder;

Fig. 2 is a schematic showing of an electromagnetic type of recorder.

One method of application is shown in Fig. 1 wherein the point electrode l is of a form similar to that used in spark recorders, which is placed nearly in contact with the moving paper 4 upon which the record is made. Beneath the paper 4 is placed another electrode 2 which is in the form of a flat conducting plate. The surface 3 of this electrode adjacent the paper is especially prepared by coating it with a finely divided colored powder, preferably in colloidal form, held to the surface by a light insulating binder. Upon applying a potential of sufficient value to the conductors 5 and 6, an electrostatic field is created between electrodes I and 2 of such value as to cause some of the particles adhering to the electrode 2 to be pulled upward and deposited'on the record sheet 4. It is not necessary to apply a potential to conductors 5 and 6 of such a value as to cause a spark to jump between the electrodes l and 2. Depending upon the composition of the powder, the colored particles may carry either a positive or a negative electric charge, and therefore the direction of application of the electrostatic field must be such as to pull the particles off the electrode 2 toward the paper in the direction of the electrode I.

It may readily be seen that by coating the electrode 2 with powders of different colors, different colored records may be obtained.

Electrostatic recorders have been proposed heretofore wherein a colored liquid is drawn through a capillary tube and caused to be drawn on to a recording sheet by an electrostatic field. This structure presents certain disadvantages in that 5 the capillary tube may become clogged or broken, in which case the apparatus would be rendered inoperative.

In the present invention the use of a finely divided dry material placed directly upon one of 10 the electrodes eliminates the disadvantages inherent in the structure disclosed in Kitsee Patent No. 1,097,131.

Another method of application is shown in Fig.

2 wherein the surface ID of the member i l is covl5 ered with a finely divided colored powder made magnetic by the addition of some magnetic substance such as finely divided nickel or iron. This powder is held on the surface by a light binding material as in the previous case. The paper 4 20 passes over member in the same manner as shown in Fig. 1. Directly above paper 4 is placed a small rod 1 of iron or other magnetizable material which terminates in a point 9 above and closely adjacent to the surface of the paper 4. By passing an electric current through the winding 8 by any suitable means which may be connected to the conductors l2 and I3, or otherwise suitably magnetizing the member I, the magnetic particles carried on the surface i0 may 30 be attracted and pulled oil? with sufilcient force to cause them to be deposited upon the under side of the paper 4.

In the structures shown in Figs. 1 and 2, the paper 4 is uniformly or otherwise moved in the 35 direction indicated by the arrows so that continuous records may be made. Obviously, several different records may be made upon a single strip by making the various records in different colors.

It will be understood that the above description and accompanying drawing comprehend only the general and preferred embodiments of my invention and that various changes maybe made therein within the scope of the appended 45 claims without sacrificing any of the advantages of this invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental 50 purposes, without the payment of any royalty thereon.

I claim:

1. An electromagnetic recording device, comprising a coil, a magnetic core within said coil having an end of reduced section extending from said coil, a marking medium containing a finely divided magnetic material spaced from the reduced section end 01' said core, a movable record sheet disposed between said core and said marking medium and means for supplying recording currents through said coil for causing some of saidmarkingmediumtobedrawn toward said core on to said record sheet.

2. In an electromagnetic recordingvdevice a marking element comprising a finely divided magnetizable material, a coloring material and a I 

